Feb. 12, 2013
Steve Cole
Headquarters, Washington
202-358-0918
stephen.e.cole@nasa.gov
Alan Buis
Jet Propulsion Laboratory, Pasadena, Calif.
818-354-0474
alan.buis@jpl.nasa.gov
Janet Wilson
University of California, Irvine
949-824-3969
janethw@uci.edu
RELEASE: 13-049
NASA SATELLITE DATA FIND FRESHWATER LOSSES IN MIDDLE EAST
WASHINGTON -- A new study using data from a pair of gravity-measuring
NASA satellites finds that large parts of the arid Middle East region
lost freshwater reserves rapidly during the past decade.
Scientists at the University of California at Irvine (UC Irvine);
NASA's Goddard Space Flight Center in Greenbelt, Md.; and the
National Center for Atmospheric Research in Boulder, Colo., found
during a seven-year period beginning in 2003, parts of Turkey, Syria,
Iraq and Iran along the Tigris and Euphrates river basins lost 117
million acre feet (144 cubic kilometers) of its total stored
freshwater. That is almost the amount of water in the Dead Sea. The
researchers attribute about 60 percent of the loss to pumping of
groundwater from underground reservoirs.
The findings, to be published Friday, Feb. 15, in the journal Water
Resources Research, are the result of one of the first comprehensive
hydrological assessments of the entire Tigris-Euphrates-Western Iran
region. Because obtaining ground-based data in the area is difficult,
satellite data, such as that from NASA's twin Gravity Recovery and
Climate Experiment (GRACE) satellites, are essential. GRACE is
providing a global picture of water storage trends and is invaluable
when hydrologic observations are not routinely collected or shared
beyond political boundaries.
"GRACE data show an alarming rate of decrease in total water storage
in the Tigris and Euphrates river basins, which currently have the
second fastest rate of groundwater storage loss on Earth, after
India," said Jay Famiglietti, principle investigator of the study and
a hydrologist and professor at UC Irvine. "The rate was especially
striking after the 2007 drought. Meanwhile, demand for freshwater
continues to rise, and the region does not coordinate its water
management because of different interpretations of international
laws."
Famiglietti said GRACE is like having a giant scale in the sky. Within
a given region, rising or falling water reserves alter Earth's mass,
influencing how strong the local gravitational attraction is. By
periodically measuring gravity regionally, GRACE tells us how much
each region's water storage changes over time.
"GRACE really is the only way we can estimate groundwater storage
changes from space right now," Famiglietti said.
The team calculated about one-fifth of the observed water losses
resulted from soil drying up and snowpack shrinking, partly in
response to the 2007 drought. Loss of surface water from lakes and
reservoirs accounted for about another fifth of the losses. The
majority of the water lost -- approximately 73 million acre feet (90
cubic kilometers) -- was due to reductions in groundwater.
"That's enough water to meet the needs of tens of millions to more
than a hundred million people in the region each year, depending on
regional water use standards and availability," said Famiglietti.
Famiglietti said when a drought reduces an available surface water
supply, irrigators and other water users turn to groundwater
supplies. For example, the Iraqi government drilled about 1,000 wells
in response to the 2007 drought, a number that does not include the
numerous private wells landowners also very likely drilled.
"Water management is a complex issue in the Middle East -- an area
that already is dealing with limited water resources and competing
stakeholders," said Kate Voss, lead author of the study and a water
policy fellow with the University of California's Center for
Hydrological Modeling in Irvine, which Famiglietti directs.
"The Middle East just does not have that much water to begin with, and
it's a part of the world that will be experiencing less rainfall with
climate change," said Famiglietti. "Those dry areas are getting
dryer. The Middle East and the world's other arid regions need to
manage available water resources as best they can."
Study co-author Matt Rodell of Goddard added it is important to
remember groundwater is being extracted unsustainably in parts of the
United States, as well.
"Groundwater is like your savings account," Rodell said. "It's okay to
draw it down when you need it, but if it's not replenished,
eventually it will be gone."
GRACE is a joint mission with the German Aerospace Center and the
German Research Center for Geosciences, in partnership with the
University of Texas at Austin. For more about GRACE, visit:
http://www.nasa.gov/grace
and
http://www.csr.utexas.edu/grace
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